Conduit bend



Dec.1,1942. c. H. NQRDELL 2,303,949

CONDUIT BEND Filed Jan. 1s, 1940 5 Sheng-sheet 1 Dec. 1, 1942. c. H.NORDELL CONDUIT BEND Filed Jan. 1:5, 1940 5 sheets-sheet 2 lill/[lill@Z'H/ofdell y @fw Y Filed Jan. 13, 1940 c. H. NoRDELL GONDUIT BEND 3Sheets-Sheet 5 jcdej@ faz? fl /afJe ZZ Patented Dec. 1, 1942 UNITEDSTATES Param OFFICE CONDUI'l` BEND Carl H. Nordell, Chicago, Ill.Application January 13, 1940, Serial No.V 313,660

(Cl. 13S-39) 7 Claims.

This invention relates to fluid conduit bends, including pipe bends, andhas for its principal object .to provide bends in which the resistanceto flow and erosion resulting therefrom are minimized to a great extent.

Other objects, advantages and capabilities of the invention will appearfrom the following description of preferred embodiments thereof, takenin conjunction with the accompanying drawings, in which:

Figure 1 is a sectional view showing a 90 degree bend and associatedconduits embodying my invention;

Fig. 2 is a sectional View taken on the line 2-2 of Fig. 1;

Fig. 3 is a sectional view of a U-bend embodying my invention;

Fig. 4 is a sectional view of a short 90 degree bend embodying myinvention;

Fig. 5 is a sectional view taken on the line 5 5 of Fig. 4;

Fig. 6 is a sectional view of a 90 degree bend intended for rectangularconduits;

Fig. 7 is a sectional View taken on the line 'l-l of Fig. 6

Fig. 8 is a sectional View of a modified 90 degree bend embodying myinvention, and y Fig. 9 is a sectional view taken on the line 9 9 ofFig. 8.

Referring to the drawings and particularly to Figs. l and 2, my improvedbend is designated by the reference numeral I 0, this particular bendbeing adapted for bell and spigot work. The communicating conduits aredesignated by the reference numeral I I. The axis of the bend is acurved line designated by the reference numeral l2. Since this line iscurved, it defines a plane of the axis of the bend which, forconvenience of reference, will be designated the main plane of the bend.

The outer wall of the bend, that is, the outer wall which lies in themain plane, is of substantially circular form, being approximately aquadrant of a circle. The inner wall of the bend which lies in the mainplane, is in the form of a segment of an ellipse, this ellipse beingshown in dotted lines in Fig. l. The minor axis of the ellipsepreferably lies substantially in the apical direction of the bend andconsequently passes through the center of the outer surface.

Owing to the relation of the inner wall referred to above, the diameterof the bend in the main plane thereof is larger than the diameter of theends of the bend, these ends being preferably circular to conform to theconduits Il.

ferred that the cross-sectional area of the bend in the apical plane isbetween about 10% and about greater than the cross-sectional area of theends of the bend or the cross-sectional area of the conduits Il. Forbends having a smooth internal surface the enlargement ofcross-sectional area may be somewhat less than 10%, while for bendshaving a rough internal surface and particularly where the bends are oflarge size, the enlargement may be somewhat larger than 30%. Preferablythe cross-section of the bend in its apical plane, as shown in Fig. 2,is substantially circular although it may be in the form of a distortedcircle in order to provide a cross-sectional l area which falls withinthe degree of magnitude indicated. Where such distortion is necessary itis preferred to increase the area on the inner side of the bend assuggested in dotted lines in Fig. 2.

It will be noted that the inner wall, which is of elliptical contour, issubstantially tangential to the adjacent portions of the conduits. Thewall of elliptical section is displaced inwardly of the correspondingcircular quadrant i3. This displacement is preferably between 5% and 15%of the normal conduit diameter when the maximum cross-section, as shownin Fig. 2, is substantially circular. When this cross-section is ofoblate form the displacement may be correspondingly less. The bend hasbeen defined principally with reference to the outer contour, the innercontour and the cross-section in the apical plane of the bend. The wallsof the bend are preferably faired from the apical cross-section towardsthe It is prebend.

ends of the bend.

In the case of a U-bend as shown in Fig. 3, the

structure is substantially similar, the outer contour of the bend ispreferably semi-circular while the inner contour conforms substantiallyto a semi-ellipse, the minor axis of which coincides with the apicalplane of the bend. The crosssectional area of the-bend in the apicalplane is preferably between about 10% and about 30% greater than thecross-sectional area of the ends of the bend. As in the case of theembodiment of Fig. 1, the cross-section of the U-bend of Fig. 3 in itsapical plane is either circular or of substantially elliptical form. Inthe case of sharp bends the ellipse which determines the inner contourof the bend tends to become flatter and the crosssection may be madeoblate in order to provide cross-sectional area within the limit stated.

As in the previously described embodiment, the walls of the bend arefaired from the cross-section in the pical plane towards the ends of theIn the case of short bends as shown in Fig. 4, the ellipse defining theinner contour becomes relatively short and considerably fiattened. Inother words, it becomes an ellipse having a short major axis and arelatively short minor axis. In this case, in order to provide across-sectional area in the apical plane of the bend, which is betweenand 30% greater than the cross-sectional area of the ends of the bend,it is necessary to increase the diameter of the bend in a direction atright angles to the main plane of the bend over the diameter in the mainplane of the bend. In this case the cross-section of the bend in itsapical plane is preferably approximately an ellipse in which the minoraxis lies in the main plane of the bend and is preferably displacedsomewhat towards the inner contour of the bend, as is shown in Fig. 5.In Figs. 2 and 5 I show in dotted lines I4 the normal cross-section ofthe end of the bend.

The inner and outer bend contours as defined above are suitable for usewith co-nduits of rectangular cross-section. Such a bend is shown inFig. 6, with inner and outer contours substantially similar to thoseshown in Hg. 4 in connection with bends for conduits of circular form.To obtain a cross-sectional area in the apical plane with the desiredenlargement it is preferred to increase the average dimension of thebend at right angles to the main plane of the bend. This is preferebalyattained by increasing the height of the inner wall of the bend, asshown in Fig. 7.

In the embodiments of the invention described above, the inner and outercurved contours have been substantially angularly coextensive. In somecases it is advantageous to extend the inner curved contour through agreater angle than the outer curved contour. Thus, as shown in Fig. 8,the inner contour may subtend an angle of 90 degrees at the intersectionof the normals to the tangents at the ends of the curved portion of theinner contour, and the curved portion of the outer contour subtends alesser angle at this point of intersection. The extremities of thecurved portion of the inner contour lie opposite tangential portions ofthe outer contour.

In this embodiment of the invention also, the cross-sectional area ispreferably between 10% and 30% greater than the cross-sectional area atthe ends of the bend. In this embodiment of the inventionthe-cross-section of the bend in the apical plane of the bend may besubstantially circular in form or it may be substantially elliptical inform, the minor axis of the ellipse lying in the main plane of the bend.As in the embodiments of the invention described above, the walls of thebend are faired from this major cross-section into the circular ends ofthe bend.

My improved bends possess a radically lower resistance to flow of fluidswhen compared with bends previously known and consequently they do notincur the loss of head or mechanicalerosion of prior bends. Further, myimproved bends are remarkably independent of variations due to roughnessof the inner surface.

Although the invention has been disclosed in connection with thespecific details of preferred embodiments thereof, it must be understoodthat such details are not intended to be limitative of the inventionexcept in so far as set forth in the accompanying claims.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patents of the United States is:

1. A hydraulic fluid conduit bend having an outer curved surface ofsubstantially segmentary circular form, an inner surface which conformssubstantially to a segment of an ellipse having its minor axis insubstantial alignment with the apex of the bend, said conduit having anapical cross-sectional area substantially 10% to 30% greater than thecross-sectional area at the ends of the conduit, whereby the bend willoffer a resistance to flow of the hydraulic fluid substantially lessthan that offered by a corresponding bend of uniform cross-sectionalarea.

2. A hydraulic fluid conduit bend having an outer curved surface ofsubstantially segmentary circular form, an inner surface which conformssubstantially to a segment of an ellipse, said conduit having an apicalcross-sectional area substantially 10% to 30% greater than thecrosssectional area at the ends of the conduit, the apical cross-sectionbeing of substantially elliptical form and the walls of the bend beingfaired from that cross-section to the ends of the bend, whereby the bendwill offer a resistance to flow of the hydraulic fluid substantiallyless than that offered by a corresponding bend of uniform crosssectionalarea.

3. A fluid conduit bend having an outer curved surface of substantiallysegmentary circular form, an inner surface which conforms substantiallyto a segment of an ellipse, the inner curvature ex-l tending over agreater angle than the outer curvature, said conduit having an apicalcross-sectional area substantially 10% to 30% greater than thecross-sectional area at the ends of the conduit, the apicalcross-section being of substantially elliptical form and the Walls ofthe bend being faired from that cross-section to the ends of the bend.

4. A hydraulic fluid conduit bend having a low resistance coefcient,said bend comprising sub'- stantially rectangular ends, an outer curvedsurface substantially a segment of a circle, and an inner surfacesubstantially a segment of an ellipse, said conduit having an apicalcross-sectional area of substantially 10% to 30% greater than thecross-section at the ends, the average width of the bend at its apex ina direction at right angles to the main plane of the bend being greaterthan the corresponding dimension at the ends.

5. A fluid conduit bend having substantially rectangular ends, an outercurved surface substantially a segment of a circle, and an inner surfacesubstantially a segment of an. ellipse, said conduit having an apicalcross-sectional area of substantially 10% to 30% greater than thecrosssection at the ends, the width of the bend on the inner side and ina direction at right angles to the main plane of the bend being greaterthan the corresponding dimension at the outer surface of the bend and atthe ends cf the bend. l

6. An integral hydraulic fiuid conduit bend having a lowY resistancecoeiicient, said bend comprising ends conformed for attachment to pipesor the like having an inside surface which in its medial section takenin the plane of the bend'presents an outer circular arc extendingthroughout the angle of the bend and substantially tangent to linesextending in the directions of pipes attached to the bend, the insideofthe bend in said cross-sectional plane conforming to a portion "of anellipse, the passageway through said bend having an apicalcross-sectional area substantially 10% to 30% greater than thecross-secticnal` area at the ends thereof.

7. In integral hydraulic fluid conduit bend having a low resistancecoecient, said bend comprising ends conformed for attachment to pipes orthe like, having an inside surface which in the medial section taken inthe plane of the bend presents an outer circular arc extendingthroughout the angle of the bend and substantially tangent tocorresponding lineal elements of pipes attached thereto, the inside ofthe bend in said cross-sectional plane conforming to a portion of anellipse, said bend having an apical cross-sectional area substantially10% to 301% greater than the cross-sectional area at the ends thereof,

the apical cross-section being of substantially elliptical form and theWalls of the bend being faired from such elliptical cross-section to theends of the bend.

CARL H. NORDELL.

